The UK government has breached international, EU and its own domestic laws by selling arms to Saudi Arabia that were used in its military campaign in Yemen, according to a leading international lawyer.

An EU draft resolution in February criticising arms trade with Saudi Arabia noted it is the UK’s biggest customer for weapons. Last year, the UK supplied export licenses for almost $4.3bn of arms to Saudi.

Speaking to a select committee on arms exports and control made up of UK politicians, Philippe Sands QC said Britain had “not asked the right questions” when it came to whether or not it should sell arms to the kingdom for use during its offensive into Yemen.

“Having asked the wrong questions, it has reached answers that are implausible,” said Sands who spoke in his capacity as a barrister but is also a law professor at University College London.

Sands and his team had been asked by Amnesty, Oxfam and Safer World to provide a legal opinion on whether the UK was breaking any laws by continuing to sell weapons to Saudi Arabia that it knew could be used in its more than year-long campaign in Yemen.

“It appears clear that coalition forces are engaged in violations of international humanitarian law,” Sands said.

“In those circumstances, an assurance given by the Saudis does not appear to be worth the paper it is printed on. If I were a minister, to rely on such an assurance in the face of a report by a Security Council group of experts … I would be extremely anxious.”

The breaches of the UK government’s continued weapons exports, he said, were in relation to articles six and seven of the international arms trade treaty, the EU common principles, and the UK’s own laws.

The government has not acknowledged that there have been any breaches of international humanitarian law by the Saudis during the aerial campaign, in which UK-made arms are being used.

Sands said the government’s investigations into the accusations had so far relied on “reassurances from the Saudi authorities,” which was not good enough under the law.

“As a result of the legal obligations imposed on the United Kingdom’s government… you can’t just rely on reassurances of others and you can’t just say it is for others to form a view on this, not governments.

The arms trade treaty specifically mentions the obligations of governments to form their own conclusions, he added.

The UN and human rights groups have repeatedly criticised all sides in Yemen of committing violations and not doing enough to protect civilians in the conflict that has claimed more than 6,000 lives.

A government memo, recently circulated to MPs on the committee and read out to Sands stated that: “The government is currently satisfied that extent licences for Saudi Arabia are compliant with the UK’s export licensing material.”

The message emphasised “in particular, we note that the Saudi-led coalition is not targeting civilians.”

Weasel words

“It depends what you mean by they’re not targeting civilians, again they are slightly weasel words,” replied Sands when asked about this statement.

“It is a form of words that is accurate but does not reflect the totality of the story.”

“Is there someone in Riyadh deciding that there are a group of civilians they wish to target and deciding to take them out? No. Is there a situation in which entire towns or entire areas are being targeted? We know that to be the case.

“And it follows from that … that is in its face a violation of humanitarian international law.”

Sands acknowledged that there were situations where non-combatants could be hit without it being a breach of international law.

“War is bad wherever it happens and inevitably there will be circumstances where non-combatants - without being explicitly targeted - are injured or are killed.

“The crucial question is terms of engagement and what you do when faced with a situation where civilian deaths are inevitable.”

In January, after a leaked UN report that accused the Saudi-led coalition of conducting multiple air strikes that hit civilians at refugee camps, wedding parties and factories, the UK's Middle East minister Tobias Ellwood accused UK politicians who demanded an immediate ban on arms sales to the kingdom of "a kneejerk reaction".

The minister stated: "We need to see evidence [of the use of UK-made weapons] to make firm judgements rather than [basing them] on hearsay, and indeed, photographs."

He called for Saudi to probe its own conduct in Yemen.

In contrast, Sands went on to say that he had been troubled by some of the incidents he'd read about.

“We have given in our opinion 10 specific examples that I have to say troubled us very greatly,” he said.

“What appears to be going on in Yemen in terms of entire communities being treated as targets, not just particular buildings ... but an entire town is, on its face, seriously problematic.”

When asked about how the Saudi's alleged use of cluster munitions, something in which the UK has no involvement, should impact the decision of whether to continue selling arms to the kingdom, he said ministers should “want to know more” about the actions of people to whom they provided arms.

“It is not dispositive,” he said, “but I think you would want to form a view. Essentially what you want to know is are the people taking these decisions in Saudi Arabia likely to be the kind of people who are taking advice to ensure reasonable minimum commitments and standards and obligations are being complied with.”

“It is a reasonable factor to take into account in forming a view as to what is going to happen if you supply certain arms to that particular country.”